I just installed nx-server on a fresh installation of Ubuntu 11.10. I've also followed the instructions as in Using NX with Unity in 11.10 to specify the session I want to be loaded.
It works all right, and I can play with unity-2d or with gnome-classic by just changing the setting of the nx-client.
There is just one glitch remaining, that is that, regardless of the session launched or the theme chosen in system settings, the gtk controls are un-themed, and are just plain ugly. It's like when gnome-settings-daemon is not running if you know what I mean (yes I checked it was running). The picture posted in the question before mentioned (although showing a different problem) explains it all.
Any possible fix?